Follow these tips when using Contacts Sync for the first time:
- Make sure that you've given Contacts Sync access to your Mac Contacts. Otherwise, the app won't be able to sync your contacts. To ensure that the app has access, go to your Mac System Preferences > Security & Privacy > Privacy > Contacts.
- Next, configure the app to sync the desired accounts. Keep in mind that your Mac contacts can be composed of several accounts specified in your Mac System Prefernces. By default, the app will sync Google with iCloud. Read more about how to configure your accounts at: https://playaapps.zendesk.com/hc/en-us/articles/226399847-How-To-Select-2-Accounts-to-Sync
- For best results, disable your Google contacts in your Mac System Preferences, if you haven't done so already. Read more about it at https://playaapps.zendesk.com/hc/en-us/articles/226488587-Should-I-disable-Google-contacts-in-my-Mac-System-Preferences-
- Before syncing with Google for the first time, eliminate any duplicates by visiting https://contacts.google.com/suggestions
- If it's the initial sync, and you can treat either your Google or Mac contacts as your "master" list, I would suggest using either the "Google Contacts -> Mac" sync mode or the "Mac Contacts -> Google" sync mode. Otherwise, perform a 2-way sync. After your first sync, I would generally recommend using a 2-way sync.